FUNCTIONAL DESCRIPTION
FOX61xLEDE1 19
5 Functional description
This section gives the detailed functional description of the LEDE1 unit as a
P12 access unit in the FOX61x subrack.
Section "P12 termination modes" (page 19) describes the supported P12
traffic signal formats.
The section "Protection" (page 21) presents the available traffic protection
features.
5.1 P12 termination modes
The LEDE1 unit provides different P12 termination modes for the E1 ports.
The termination modes define
• the expected signal structure,
• the timing characteristics,
• the usage for a specific application, e.g. V5 uplink.
The LEDE1 unit supports terminated and transparent P12 transport modes.
Structured signals can be transported in a terminated mode or a transparent
mode. Unstructured signals are transported in a transparent mode.
The termination modes of all E1 ports are configurable independently.
For more information regarding P12 termination modes, cross connections
and CAS configuration please refer to FOX61x TDM Services.
5.1.1 Terminated transport modes
An E1 port of the LEDE1 unit can be configured to one of the following termi-
nated transport modes:
• PCM30:
Structured according to ITU-T G.704, with CAS, without CRC4.
• PCM30C:
Structured according to ITU-T G.704, with CAS, with CRC4.
• PCM31:
Structured according to ITU-T G.704, without CAS, without CRC4.
• PCM31C:
Structured according to ITU-T G.704, without CAS, with CRC4.
In the above terminated transport modes, the time slot 0 of the P12 signal
is analysed in the receive direction (from the network interface) and
regenerated in the transmit direction.
Cross connection and protection switching (P0-nc SNCP/I) is established
on the P0-nc (n x 64 kbit/s) traffic signal layer.
There are two specific termination modes used for the V5 application:
• V5 Uplink:
Structured according to ITU-T G.704, with CRC4.
• V5 Uplink NCI:
Structured according to ITU-T G.704, without CRC4.
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